[Etherpad] Lower HEALTCHECK interval to avoid Traefik ignoring

pica-etherpad/Dockerfile

@@ -67,7 +67,7 @@ RUN apt-get update && \
     rm -rf /var/lib/apt/lists/*
 
 EXPOSE 8080
-HEALTHCHECK CMD curl --fail http://localhost:8080 || exit 1
+HEALTHCHECK --interval=20s --timeout=3s CMD curl --fail http://localhost:8080 || exit 1
 WORKDIR /opt/etherpad-lite/
 USER etherpad